Encoding Diffusion: Advanced gradient design and relaxation-weighting
Filip Szczepankiewicz1
1Lund University, Sweden

Synopsis

This lecture will explore and illustrate how additional measurement dimensions can be added to conventional diffusion MRI. We motivate the effort to use 'multidimensional' MRI and describe the principles of tensor-valued as well as diffusion time dependent encoding. We also overview how dMRI can be combined with T1 and T2-weighting. Finally, we will briefly survey the 'uninvited' effects that may confound the measurement.

Overview

Building on the basics of diffusion encoding, this lecture will explore how additional measurement dimensions can be added to conventional diffusion MRI. First, we will motivate the effort to use 'multidimensional' MRI [1,2]. Second, the principles of tensor-valued diffusion [2,3] and time-dependent diffusion [4] will be explained and its practicalimplementation will be illustrated. Third, the incorporation of T1 and T2-weighted sequences will be explored [5]. Finally, we will briefly survey the 'uninvited' effects that may confound the measurement [2].

Acknowledgements

We thank the Swedish Research Council (2021-04844) and the Swedish Cancer Society (22 0592 JIA) for research grants.

References

  1. Benjamini D, Basser PJ. Multidimensional correlation MRI. NMR Biomed. 2020 Dec;33(12):e4226. doi: 10.1002/nbm.4226. Epub 2020 Jan 7.
  2. Szczepankiewicz F, Westin CF, Nilsson M. Gradient waveform design for tensor-valued encoding in diffusion MRI. J Neurosci Methods. 2021 Jan 15;348:109007. doi: 10.1016/j.jneumeth.2020.109007. Epub 2020 Nov 23.
  3. Westin CF, Knutsson H, Pasternak O, Szczepankiewicz F, Özarslan E, van Westen D, Mattisson C, Bogren M, O'Donnell LJ, Kubicki M, Topgaard D, Nilsson M. Q-space trajectory imaging for multidimensional diffusion MRI of the human brain. Neuroimage. 2016 Jul 15;135:345-62. doi: 10.1016/j.neuroimage.2016.02.039. Epub 2016 Feb 23.
  4. Arthur Chakwizira, Carl-Fredrik Westin, Jan Brabec, Samo Lasič, Linda Knutsson, Filip Szczepankiewicz, Markus Nilsson. Probing restricted diffusion and exchange using free gradient waveforms: validation by numerical simulations. arXiv:2111.11094 [physics.med-ph] 2021
  5. Slator PJ, Palombo M, Miller KL, Westin CF, Laun F, Kim D, Haldar JP, Benjamini D, Lemberskiy G, de Almeida Martins JP, Hutter J. Combined diffusion-relaxometry microstructure imaging: Current status and future prospects. Magn Reson Med. 2021 Dec;86(6):2987-3011. doi: 10.1002/mrm.28963. Epub 2021 Aug 19.
Proc. Intl. Soc. Mag. Reson. Med. 30 (2022)